So you jacked up your truck to feel like you’re driving Grave Digger. Is it legal ... or safe?

Question: Considering the money invested by the auto industries to make automobiles safer and traffic crashes more survivable, how can it be legal for individuals to raise their pickup trucks such that in a crash they will impact above a standard automobile’s bumper?

How can it be legal for the drivers of these pickup trucks to embellish the front bumper of their vehicle with massive steel custom bumpers which ensure that anyone struck by their truck will suffer maximum damage and/or injury?

If such modifications assist in off-roading or farm activities, then why are these vehicles not restricted as are tractors and other farm implements?

It is inconceivable to me that such modifications can be considered street legal or in any way safe.

Never miss a local story.

Sign up today for unlimited digital access to our website, apps, the digital newspaper and more.

Answer: As we’ve seen before, and I’m sure we’ll see again, street-legal and safe are often related, but not always equivalent. Some of those jacked up trucks may be legal, but many of them are not.

You’re right about the potential for damage and injury from mismatched bumper heights.

And raising (or lowering) a vehicle causes more problems than just bumper issues. We’ll look at the risks and the rules related to modified vehicle heights.

Before a manufacturer can sell a vehicle in the United States, that car or truck has to conform to federal safety standards. Skilled engineers design these vehicles to meet steering, roll-over and crash requirements.

It seems presumptuous to take a vehicle that will be used primarily for street driving and make significant modifications to ride height. Just because I can go buy a lift kit and install it on my truck doesn’t mean I’m smarter or know better than the engineer who designed it.

The further the deviation from the factory specs, the more severe the problems. Let’s list a few:

Handling: Raising a vehicle changes its center of gravity. Full-size SUVs and trucks already suffer from an increased propensity to roll over, and making them taller just exacerbates the problem. Raising or lowering a vehicle changes the geometry of the suspension and can negatively affect traction and steering.

The common assumption is that lowering a car increases traction, but when a lowered car has extreme camber (that’s when the wheels look like they’re not on straight) traction is reduced, especially during braking.

Braking: Part of jacking up a truck includes adding bigger tires. It’s pretty much a requirement, because a tall truck with factory-size tires just looks silly. But those big tires add a lot of rotating mass, and if the truck owner doesn’t upgrade the brakes at the same time, stopping distances will increase.

Visibility: Sure, you can see farther when you’re jacked up above the other cars, but what you won’t see is the kid crossing the street in front of your bumper. Or if you’re way up there, a small car.

Now for the rules. The Washington Administrative Code (WAC) sets the maximum bumper height of a vehicle based on vehicle type and, in the case of trucks, gross vehicle weight rating (GVWR). For passenger vehicles (including SUVs), that’s 22 inches, measured from the ground to the center of the bumper. For trucks, it ranges from 24 to 28 inches for the front bumper and 26 to 30 inches for the back bumper.

There are rules about lowering cars too, but the limits are almost self-enforced. No part of a car can be lower than the lowest part of the rim of the wheel (the metal part, not the rubber part – that’s the tire). Make your car lower than your rims, and there’s a good chance you’ll end up grinding it on the pavement until it reaches a legal ride height.

The custom bumpers mentioned in the question are probably illegal. On my grandpa’s old Ford F250 the factory bumper was just a chunk of steel bolted to the frame. Today’s bumpers are engineered to protect occupants in a crash.

The law requires bumpers to meet the crash absorption standards for the model year of the vehicle. If you’re an engineer familiar with federal crash standards and you do all the math, I suppose you could build a legal homemade bumper. But I suspect that doesn’t fit the description of most home-made bumper builders.

Trucks are a useful, and sometimes necessary tool. But truck owners should realize that there is additional risk and drive accordingly.

I’ll leave you with a little crash data. A study by American Association of Motor Vehicle Administrators found that while light trucks make up about one third of the vehicles on the road, they’re involved in about half of the two vehicle fatal crashes. The same study found that lifting a truck to the maximum legal limit nearly quadrupled the likelihood of a rollover.

We’re all in this together. Let’s travel with care.

Road Rules is a regular column on road laws, safe driving habits and general police practices. Doug Dahl is the Target Zero Manager for the Whatcom County Traffic Safety Task Force. Target Zero is Washington’s vision to reduce traffic fatalities and serious injuries to zero by 2030. For more traffic safety information visit TheWiseDrive.com. Ask a question.